• Hybrid-PBL;
  • LBL;
  • large classroom;
  • biochemistry


  1. Top of page
  2. Abstract
  3. Methods
  4. Results
  5. Discussion
  6. Acknowledgments
  7. References

As a result of enrollment expansion, increasing numbers of students are entering into medical school in China. This combined with a shortage of teachers, means that the learning environment typically consists of a large classroom setting with traditional lecture-based learning (LBL) as the major mode to teaching and learning. In this article, we investigate the preferences for hybrid problem-based learning (hybrid-PBL) or LBL in a large classroom setting. Two hundred five second-year undergraduate students in Third Military Medical University were randomly divided to two groups. The hybrid-PBL group contained 101 students and was taught by hybrid LBL (60%) and tutor-less PBL(40%) in a large classroom. The LBL group consisted of 104 students and was taught by LBL in a large classroom too. Post-teaching performance was assessed by multiple choice questions, short-essay questions, and case-analysis questions, while the students' teaching preferences and satisfaction were assessed by questionnaires. Analysis of the results of both groups in the examination of biochemistry revealed significantly higher scores on short-essay questions and case-analysis questions in the hybrid-PBL group. Students considered hybrid-PBL to be an effective learning method and favored it over the lecture format. Furthermore, students reported positive effects of hybrid-PBL in terms of additional learning resources, critical thinking, and fun learning experiences. These results suggest that hybrid-PBL is better than the traditional LBL method at improving students' basic knowledge and problem-solving skills. Students preferred hybrid-PBL and were satisfied with it. The tutor-less PBL pattern in a large classroom setting may be feasible in Chinese medical schools. © 2012 by The International Union of Biochemistry and Molecular Biology, 41(1):5–10, 2013

China like many other countries has a shortage of doctors, as a result there has been a significant increase in the number of students entering medical school. At the same time there has been little increase in the amount of teachers. Together these factors result in traditional lecture-based learning (LBL) in a large classroom (over 100 students) as the major mode of teaching and learning in Chinese medical school [1]. Although there are ways to liven up LBL and strategies to make it more effective, it is mostly passive learning [2]. Lectures usually do not stimulate learners to construct explanatory models and to elaborate when acquiring new information, whereas modern theories of the learning and cognition emphasize the importance of active learning.

Over the past two decades, there has been a steady increase in the number of medical colleges with a problem-based learning (PBL) curriculum [3]. The educational value and impact of using small group learning, a student-centered approach, and PBL have all been supported by both practice and research [4-6]. Today, experts in medical education largely agree that there are differences in the effects of PBL as compared with LBL. PBL is often favored over conventional education by both students and teachers. There is evidence which show that PBL is associated with a higher gain in medical competencies, in particular in interpersonal and cognitive domains [7, 8]. In addition, graduates of PBL curricula may retain their knowledge over a longer period of time and may be better prepared for life-long learning, that is keeping up with the development of medical knowledge [5].

Even though there is a significant body of evidence demonstrating the advantages of PBL over traditional LBL, a study has also suggested that PBL is not superior to LBL in all aspects of learning [9]. Furthermore, most studies on the effectiveness of PBL originate from observations made in a small-group setting, usually involving five to nine students with a tutor supervising each group. Therefore, it cannot be assumed that introduction of PBL as a course delivery technique will automatically lead to enhanced student learning, especially in a large classroom setting with tutor-less groups. The superiority of PBL over standard course delivery techniques must be proven for each individual PBL delivery method.

Since traditional PBL delivery to small groups of students involves the supervision of group processes by a tutor, this methodology is associated with considerably higher costs when compared with traditional lectures given to large groups of students. Here, we describe an approach where PBL cases are delivered to large groups of up to 101 students facilitated by a single course instructor within undergraduate biochemistry courses. Our results show that this approach leads to increased student satisfaction. More importantly, the study that we conducted within a course delivered through a hybridization of PBL and LBL format showed a significant improvement of students' basic knowledge and problem-solving skills.


  1. Top of page
  2. Abstract
  3. Methods
  4. Results
  5. Discussion
  6. Acknowledgments
  7. References

Participating Students

All of the students entered Third Military Medical University directly from high schools. After experiencing basic science training for 1 year, they began the study of basic medical curriculum in the third semester. The course of biochemistry has traditionally been located in the third semester and is given on a twice weekly basis. Before the course, all of the participating students completed the basic science curriculum which includes mathematics, chemistry, physics, and biology. The 205 students who enrolled for the course in the autumn term of 2011 were assigned into two groups randomly. Group 1 was scheduled for hybrid-PBL and thus became the hybrid-PBL group, whereas the Group 2 was scheduled for LBL, as the LBL group.

Teaching Methods

Hybrid-PBL group

The hybrid-PBL group consisted of 101 students; the statistical data of the group are displayed in Table 1.

Table 1. Basic statistical data of hybrid-PBL group and LBL group
 Hybrid-PBL group (Hybrid-PBL, n = 101)LBL group (LBL, n = 104)
Mean age (years)18.818.3

The group was randomly divided into ten small groups, each comprising nine to eleven participants. The scheduled course time is 80 min, on Tuesday and Friday morning. During the fall term nine PBL cases were delivered, represent ∼40% of the course delivery time. Each case is presented to the students over the course of the session spaced at least 1 week to allow sufficient independent study. At the beginning of the class, case materials were displayed in a large lecture auditorium with students sitting in assigned groups. Usually two to three slides were shown per case. Students were asked to work within their assigned groups to assess the presented information, list various concerns/problems, hypothesize as to what might be happening, and identify issues that could not be addressed without further study. Usually 5–10 min are allotted for this initial discussion. Individual group discussions were not supervised since only one instructor was present in the classroom. These discussions were followed by an open classroom discussion with all groups participating. Then groups were encouraged to be brief and to the point so that all reports may be heard. The initial reporting group was picked in a random manner so that all groups were attentive and ready to report, but other groups also get a chance to participate in a predetermined order. During the open class discussion, detailed notes were taken on white boards by the teacher. The instructor uses guiding questions to ensure that students identify learning issues that are appropriate to the case and consistent with the learning objectives of the course. After the initial slide has been exhausted, additional case information is presented followed by individual group discussion and open classroom discussion. Information sufficient to solve the case was not revealed until the last slide. The case was concluded by discussing the final hypotheses in the random reporting format.

The questions shown in Table 2 are an example of cases given to students. Usually all 80 min of the lecture period are used for the case study. After each PBL session, all of the materials/slides and learning issues as well as the discussion notes organized into rubrics such as “problems,” “hypotheses,” and so forth are made available through an online course management system.

Table 2. Example of PBL case
Case material
A 32-year-old female is being treated with methotrexate for a recently diagnosed choriocarcinoma of the ovary, and presents with complaints of oral mucosal ulcers. The patient recalls being advised not to take folate-containing vitamins during therapy. An uncomplicated surgical exploration was performed 5 weeks ago with removal of the affected ovary. The patient has been taking methotrexate for 2 weeks and has never had any of the above symptoms before. On examination, patient was afebrile and appeared ill. Several mucosal ulcers were seen in her mouth. The patient also had some upper abdominal tenderness. Her platelet count is decreased at 60,000/mm3 [normal 150,000 to 450,000/mm3].
Guiding questions asked:
What is the most likely etiology of her symptoms?
What is the biochemical explanation of her symptoms?
What part of the cell cycle does methotrexate act on?
LBL Group

The LBL group consisted of 104 students; the statistical data of the group are displayed in Table 1.

The 104 students underwent traditional lecture-based teaching, provided by same staff with hybrid-PBL group. The scheduled lecture time was 80 min.

Evaluation Methods

Three different approaches were used to evaluate the study:

  1. The written examination of biochemistry at the end of the semester: the students of both groups took the final examination after completion of the course. The examination was designed as a combined multiple-choice, short-essay test, and case-analysis test: 20 multiple-choice questions (two point per question, i.e. a maximum of 40 points in total could be obtained), 10 short-essay questions (four points per question were possible, so that the maximum score for this category was 40 points as well), and 2 case-analysis questions (ten point per question, i.e. 20 points is the maximum score for this category question). Standard answers for all questions were defined and handed out to the staff before students' answers in the examination were scored. The staff scoring the examinations was blinded as to the identity and group of the students.
  2. A questionnaire to investigate students' preference for either hybrid-PBL or LBL teaching was administered before and after the course. Answers were to be given to the following questions: (a) if you had the possibility to choose before the course, would you have opted for the hybrid-PBL-course/LBL course? (tick as appropriate); (b) after the experience from the course, would you now opt for the hybrid-PBL course/the LBL course if you had to choose again? (Ticked as appropriate).
  3. A second questionnaire was given to address the students' satisfaction with the hybrid-PBL course: only the participants of the hybrid-PBL group filled out this questionnaire to rate the content, framework (tutor, rooms, …) and subjective effects of the hybrid-PBL course. The questionnaires consisted of 20 questions. Answers were to be provided on five point Lickert scales ranging from 1, “strongly disagree,” to 5, “strongly agree.” In addition, students had the opportunity to comment on the contents of the tutorial, as well as on possibilities for improvement in full text.

Statistical Analysis

SPSS software (version 16.0) was used to conduct the statistical analyses of the data. Data are presented as means ± SE. For comparing the results of both the hybrid-PBL group and the LBL group in the final examination of biochemistry, we computed the mean number of points achieved by the students in each group. For comparison of overall results between the two groups, as well as for inter-group comparison of results in the categories of multiple-choice, short-essay questions, and case-analysis question, respectively, we used the alternate t-test. We also used this test for comparison of the results in the three categories of questions (multiple-choice versus short-essay) within the groups.


  1. Top of page
  2. Abstract
  3. Methods
  4. Results
  5. Discussion
  6. Acknowledgments
  7. References


As shown in Fig. 1, all of the 205 students originally included in the study sat the final examination of biochemistry. One hundred one students were from the hybrid-PBL group and 104 from LBL group. Before/after the course, 93%/97% in hybrid-PBL group and 91.3%/95.2% in LBL group completed the questionnaire on preferences for hybrid-PBL versus LBL.


Figure 1. Participations of completing final examination and questionnaires on preference for hybrid-PBL versus LBL before and after the course.

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Comparison of the Two Groups' Results in the Examination of Biochemistry

This comparison showed a significant difference between the results of the students in the hybrid-PBL group (mean 80.3 points, SD 10.1) and those in the LBL group (mean 67.8 points, SD 9.5), p = 0.041 (Fig. 2). In the multiple-choice questions category, there were no significant difference between the two groups (mean 31.6, SD 4.7 in the hybrid-PBL group versus 32.2, SD 5.2 points in the LBL group), p = 0.52. Analysis of the results in the short-essay part (p = 0.035) and case-analysis part (p = 0.012) revealed significant differences; the hybrid-PBL group with a mean of 32.2 points (SD 5.8) at short-essay part and 16.5 points (SD 2.4) at case-analysis part versus 24.3 points (SD 4.7) at short-essay part and 11.3 points (SD 3.1) at case-analysis part in the LBL group (Fig. 3).


Figure 2. Mean total score (±SE) of students from the hybrid-PBL group (hybrid-PBL, n = 101) and the LBL group (LBL, n = 104) in the final examination of biochemistry. *p < 0.05.

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Figure 3. Comparison of the two groups' results on multiple-choice, short-essay, and case-analysis respectively. *p < 0.05, N.S.: No significance.

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Comparing results in the different categories of questions within each group showed that the hybrid-PBL students reached almost identical scoring rate in their multiple-choice questions (79%), short-essay questions (80.5%), and case-analysis questions (82.5%), whereas the students who had been in the LBL course scored significantly (p < 0.05) lower in their short-essay (60.75%) and case-analysis (56.5%) than in their multiple-choice questions (80.5%) (Fig. 4).


Figure 4. Comparison of the results in the different categories of questions within groups. *p < 0.05, N.S.: No significance.

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Preference for Hybrid-PBL Versus LBL Before and After the Course

The answers to this question showed a high ratio of students in both groups with a preference for hybrid-PBL before the study, 87.1% in the hybrid-PBL group versus 85.6% in the LBL group (Fig. 5). A slight incensement (92.08%) in hybrid-PBL group and little change (86.54%) in LBL group were found for the same item after the course, indicates that hybrid-PBL course attracted more students to attend. This point was further validated by the hybrid-PBL group students with an original preference for LBL, had a greater tendency to change their attitude and to shift toward hybrid-PBL (61.54%) than students with an original preference for hybrid-PBL of which only 3.41% changed their mind (Fig. 5). These differences were also seen in the LBL group where the shift toward hybrid-PBL was higher than that from hybrid-PBL.


Figure 5. Preferences of students from hybrid-PBL group (hybrid-PBL, n = 101) and the LBL group (LBL, n = 104) before and after the course. Hybrid-PBL-Before: preferred for hybrid-PBL before course, Hybrid-PBL-After: preferred for hybrid-PBL after course, LBL to Hybrid-PBL: from LBL shift to hybrid-PBL after course, Hybrid-PBL to LBL: from hybrid-PBL shift to LBL after course.

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Questionnaire on Student Satisfaction

The hybrid-PBL students' answers to this questionnaire revealed a high overall satisfaction with the course. More specifically, students stated they had been interested in the topic of biochemistry from the beginning (mean: 4.1 on the five-point-Lickert-scale) and considered it important (4.4). They were stimulated to use additional resources (3.8), among which they named textbooks, the library in general, other students, lectures, and experts. The students considered hybrid-PBL to be an effective learning strategy (4.3) and would recommend it to other students (4.1).

The results of the questionnaire are displayed in detail in Table 3.

Table 3. Mean scores from students' answers in the questionnaire on student satisfaction (n = 195)
Statement in the questionnaireMean score(± SD), five-point-Lickert-scale from 1 to 5
I am interested in subject of this hybrid-PBL course4.1 ± 0.9
I consider the subject to be important within the frame of my studies4.4 ± 0.8
The content of the course fitted the level of my knowledge.4.0 ± 1.1
The PBL cases illustrate medical concepts.4.3 ± 0.8
The cases have motivated me to use additional learning resources.3.8 ± 1.1
The tutor guides the PBL course adequately.3.5 ± 1.3
The tutor understands the objectives and assists the group.3.4 ± 1.6
The tutor attends session and control of session for discussion is adequate.3.6 ± 1.2
The course increases my motivation to do well in the course.3.8 ± 1.0
The course encourages critical thinking at available material.3.7 ± 1.1
The course increases my motivation to participate in class3.3 ± 0.7
I will recommend this hybrid-PBL course to other students.4.1 ± 0.5
The group climate facilitated the learning process.3.6 ± 1.2
I felt well informed about the hybrid-PBL method.4.1 ± 0.6
Hybrid-PBL course was fun.4.3 ± 0.8
The learning outcome of the course was large.4.2 ± 0.9
In the hybrid-PBL course I learned something for my dealing with patients.3.4 ± 1.3
In the PBL group, I could improve my communication skills.3.2 ± 1.2
I consider hybrid-PBL to be an effective learning style for myself.4.3 ± 0.7


  1. Top of page
  2. Abstract
  3. Methods
  4. Results
  5. Discussion
  6. Acknowledgments
  7. References

In this study, we demonstrated that it may be feasible to implement hybrid-PBL as an educational strategy under the current conditions of a Chinese medical school. The hybrid-PBL approach in a large classroom setting has benefits for students' basic knowledge and problem-solving skills, as measured by written examination at the end of the semester. The results of our study therefore support earlier findings that hybrid-PBL is not only superior to LBL at students' basic knowledge but also at problem-solving skills [10].

The PBL students achieved better results in the categories of short-essay questions and case-analysis questions while no difference in the multiple-choice questions, which is consistent with Wolfram's results [11]. This fact indicates that examination testing of more complex levels of knowledge, (i.e. on the comprehension or analysis level) is more appropriate for testing the outcome of PBL [12]. An intra-group comparison of the three categories of questions further supported this hypothesis, revealing that students who had undergone the lecture-based course scored significantly lower in the short-essay part and case-analysis part, whereas their hybrid-PBL counterparts reached similar results in all categories of questions.

With regard to participation, both the hybrid-PBL group and LBL group keep a high participation rate in our study (Fig. 1). This result is not consistent with some previous reports [11, 13]. Since our university is a military medical school, all of the students are soldiers, and biochemistry is one of their basic medical training requirements, this may result in high participation.

When looking at the results of the questionnaires on students' preference for either of the two educational approaches, it is striking that a majority of the students in both groups would have preferred the hybrid-PBL course even before they had experienced it. Since PBL methodology was introduced in genetics and pathology courses before our study, and all students had received some general information on the method; we hypothesize that this preference for hybrid-PBL was an expressed attitude against the traditional system that the students were well acquainted with. After the course, however, the proportion of students favoring hybrid-PBL was increased in the hybrid-PBL group, indicating that those who now had a hybrid-PBL experience were not disappointed. Also, relatively more students changed their mind from LBL to hybrid-PBL than vice versa.

An important finding from the questionnaire distributed to the students in the hybrid-PBL course only, is the high level of students' satisfaction with the hybrid-PBL course. While the results of the questionnaire by no means provide an objective measurement of the strengths of hybrid-PBL, they do indicate that hybrid-PBL satisfies students' perceived needs in their education. In our opinion, student satisfaction by itself must be considered an important factor. It may be of particular importance that students were encouraged to extend their learning beyond the borders of the subject of biochemistry and to make use of additional learning resources [12].

Compared to classic PBL model, tutor-less PBL technique may be more suitable for Chinese medical school. Usually a large classroom setting with over 100 students and 1 teacher is the teaching and learning environment in Chinese medical school. The tutor-less PBL technique does not require additional tutors; therefore no additional funding is needed to implement this technique. To use this technique successfully, the instructor must be comfortable managing 8–10 groups of students during the open discussion phases of the PBL sessions which requires good facilitation skills. We estimate that up to 120 students could be managed by the technique described in this report. In classrooms with > 120 students, the process may break down because the time needed for group reports would create too much idle time for the majority of students [14]. Guiding questions are needed to ensure that students identify learning issues [15]. Attendance and fair distribution of workload are issues that require additional attention [16]. Another advantage of PBL conducted in a large classroom compared with small-group sessions is that all students are exposed to the same case information during each session [17]. This eliminates the need for the detailed tutor manuals that are typically used for the instruction of students in small tutor-led group meetings conducted in different rooms. In spite of the effect of tutor-less PBL, techniques on teaching and learning need to be further validated and evaluated, our results suggest that this technique can be used to improve the traditional large classroom LBL learning mode in Chinese medical school.

Ethical Approval

This study was approved by the Protocol Review Committee of the Undergraduate MD Programme and the Faculty of Health Sciences Research Ethics Board at Third Military Medical University.


  1. Top of page
  2. Abstract
  3. Methods
  4. Results
  5. Discussion
  6. Acknowledgments
  7. References

The authors thank Third Military Medical University 2011 clinical medicine students for participation in this study. They also thank Seth J. Lewin for his help at article revising.


  1. Top of page
  2. Abstract
  3. Methods
  4. Results
  5. Discussion
  6. Acknowledgments
  7. References
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